Survival outcomes and adverse prognostic factors of Langerhans cell histiocytosis: a 40-year experience from a single tertiary center in Thailand.

The survival of Langerhans cell histiocytosis (LCH) in high-income countries is favorable, with rates of over 95%. However, there are few studies from resource-limited countries. Thus, this study aimed to examine survival risk factors and outcomes of LCH patients in Thailand. A retrospective review was conducted on LCH patients aged < 15 years at Songklanagarind Hospital over 40-year period. Cox regression analysis was utilized to identify risk factors. The overall (OS) and event-free survival (EFS) rates were calculated using the Kaplan-Meier method. A total of 68 patients were included with a median age of 2.1 years. Of these, 27 (39.7%) had single-system (SS)-LCH, 17 (25.0%) had no risk organ (RO-) multisystem (MS)-LCH, and 24 (35.3%) had risk organ (RO+) MS-LCH. The 5-year EFS of patients with SS-, RO-, and RO + MS-LCH were 95.2%, 58.4%, and 44.1%, respectively (p < 0.01). MS-LCH patients had a higher reactivation rate compared to those with SS-LCH (50.0% vs. 4.3%, p = 0.02, respectively). Age < 1 year was an independent risk factor for inferior survival (HR 13.79, 95% CI: 1.5-123.4, p = 0.02). The OS and reactivation rates of LCH patients treated with our national protocol are comparable to those of high-income countries. The infant was associated with inferior survival.